Here a wafer of semiconductor has two contacts on opposite sides which are connected to a high impedance voltmeter, v. This principle is observed in the charges involved in the electromagnetic fields. Hall effect in semiconductors request pdf researchgate. It finds widespread application in magnetic field sensors and has led to a wealth of new phenomena, such as the integer and fractional quantum hall effects in twodimensional systems 3, 4. What is hall effect and what is the use of hall effect. Hall effect for ptype semiconductor physics forums. Being very simple and straight forward phenomena in physics, hall effect is a fundamental principle in magnetic field sensing and have many practical applications in our daily life. The hall effect experiment conducted by edwin hall in 1879 determines the sign of the charge carriers in current flow. Introduction in 1879 edwin hall, a graduate student at johns hopkins university, observed that when a magnetic field is applied at right angles to the direction of current flowing in a conductor, an electric field is.
The scaffold was then coated with a thin film of ntype zinc oxide, a widebandgap semiconductor. In ptype semiconductor the charge carriers are said to be positive, that is electron hole. The fundamental quantum of hall resistance is he2 25,8. In the early days of semiconductor research, this fact caused a lot of. If an electric currents is made to flow through a conductor in a magnetic field, the magnetic field will exert a transverse force on the moving charge carriers which tends to push them to one side of the conductor. This voltage is a direct measure of the magnetic field as long as the current is constant. Then how is it that the hall effect experiment for ptype.
When a magnetic field is applied perpendicular to the direction of flow of charge carriers, in a semiconductor material, charge carriers experience a force in transverse to the direction of applied magnetic field and carriers flow. The hall effect is a galvanomagnetic effect, which was observed for the first time by e. Winner of the standing ovation award for best powerpoint templates from presentations magazine. A sample of copper of thickness 18 x 106 m is placed in a 0.
Edwin hall discovered this effect in the year 1879. We observed a strong dependence of the hall like current on the magnetic field, h, the acoustic. We have seen that the charge carriers in metals are electrons which are in partially occupied conduction band. Thin film samples consisting of a semiconductor inas and two different metals aluminum and gold are investigated to determine the sign and density of the. The resistance of the semiconductor germanium ge near room temperature decreases. A current can be thought of as a negative charge moving in one direction or as a positive charge moving in the opposite direction. Theyll give your presentations a professional, memorable appearance the kind of sophisticated look that todays audiences expect. Hence the hall voltage at b 1t and i10a and t 1 mm for copper and silicone are, 0.
Experiment 14 hall effect and resistivity measurements in doped gaas. Investigating electrical conduction mechanisms in doped germanium. In studying p and ntype doping, it is natural to ask. D1 semiconductor physics and the hall effect physics 191r. Physics 441442 physics advanced laboratory the hall effect and the conductivity of semiconductors 1. Hall effect applications of hall effect electrical4u. A buildup of charge at the sides of the conductors will balance this magnetic influence, producing a measurable voltage. If positives move to the right that means that in reality electrons are moving to the left. Hall effect derivation with simple steps and applications. V is velocity of electrons at right angle to magnetic field, there is a down ward force on each electron of magnitude bev.
Hall effect and its applications in semiconductorsphysics. These steps are completely independent of the type of sample and quantitized to values he2m, where m is an integer. This demonstration shows hall effect in semiconductor materials and shows how ntype and ptype semiconductors can be identified. The hall effect also showed that in some substances especially ptype semiconductors, it is more appropriate to think of the current as positive holes moving rather than negative electrons. Hall effect describes the behavior of free charge carriers in the semiconductor when subjected to the electric and magnetic fields. Hall semiconductor resistance, band gap, and hall effect. The electric field, or hall field, is a result of the force that the magnetic field exerts on the moving positive or negative. The hall effect in metals and semiconductors in this experiment, students learn about the classical hall effect which is the basis of most sensors used in magnetic field measurements. In this experiment, the hall effect will be used to study some of the physics of charge transport in metal and semiconductor samples. The hall effect, which was discovered in 1879, determines the concentration and type negative or positive of charge carriers in metals, semiconductors. The hall effect in a metal and a ptype semiconductor required background reading tipler, chapter 10, pages 478479 on the hall effect prelab questions 1. This laboratory manual is based on a manual for a very similiar experiment from the physics 111 advanced undergraduate laboratory at uc berkeley see references. The fabrication effort, led by phd student christian kern, began with 3d direct laser writinga form of 3d printingto make a scaffold structure out of a polymer material.
Aoki, in comprehensive semiconductor science and technology, 2011. Because its electrically insulating, it has no effect on the metamaterials. The hall voltage in a semiconductor will be measured in the magnetic field of a large electromagnet. D1 semiconductor physics and the hall effect from physics 191r hall effect word version file. Hall effect, development of a transverse electric field in a solid material when it carries an electric current and is placed in a magnetic field that is perpendicular to the current. An instrument called a hall probe may now be used to measure the flux density b of a magnetic field. This causes the electron current to be deflected in a downward direction and causes a negative charge to accumulate on bottom face of slab. Hence in a semiconductor, instead of travelling in a straight line, the electrons and holes will initially take paths as shown by the dotted lines in the figure below.
It is well known that a potential applied across the semiconductor material causes the electrons within it to move in the direction opposite to that of the applied field. In the ntype semiconductor, the electric field is primarily produced due to the negatively charged free electrons. Quantum hall effect an overview sciencedirect topics. Basic semiconductor material science and solidstate physics all terrestrial materials are made up of atoms. Hall effect in electronics is explained with ntype semiconductor and ptype semiconductor in this video along with few applications of hall effect. In order to understand some of the ideas involved in theory of the hall e. The hall effect theory for a charge moving in a magnetic field, it experiences a force acting at right angles to both its direction and the direction of the magnetic field h. Harsh shukla hall sensor hall effect and its applications hall effect thruster 2. Basic physics underlying the phenomenon is explained. Reif, fundamentals of statistical and thermal physics introduction in this experiment the resistivity and hall effect in a crystal of ntype.
Hall effect hall effect derivation electronics tutorials. The existence of holes in a doped ptype semiconductor is demonstrated by the hall effect. All of we know that when we place a current carrying conductor inside a magnetic field, the conductor experiences a mechanical force to a direction depending upon the direction of magnetic field and the direction of current in the conductor. This effect consists in the appearance of an electric field called hall field eh r, due to the deviation of the charge carrier trajectories by an external magnetic field. This effect consists in the appearance of an electric field called hall field eh. Ravindran, phy02e semiconductor physics, autum 20 17 december. The hall effect offered the first real proof that electric currents in metals are carried by moving electrons, not by protons. Hall observed that when an electrical current passes through a sample placed in a magnetic. Observation of the spin hall effect in semiconductors. Integer quantum hall effect, which is the hall effect quantized into integer times e 2 h e. She hall effect in semiconductor experimentation lab university. Hall effect experiment utk department of physics and. Pdf physics of semiconductor devices manish srivastava.
Instrument manuals this lab will be graded 30% on theory, 20% on technique, and 50% on analysis. Worlds best powerpoint templates crystalgraphics offers more powerpoint templates than anyone else in the world, with over 4 million to choose from. In metal it is entirely due to the flow of electrons, in. We show that hall like current can be induced by acoustic phonons in a nondegenerate, semiconductor fluorinedoped singlewalled carbon nanotube fswcnt using a tractable analytical approach in the hypersound regime q is the modulus of the acoustic wavevector and is the electron mean free path. These kinds of sensors with typical dimensions of the sensitive element of 0. Mainly lorentz force is responsible for hall effect. The hall coefficient obtained may be used to determine the density of the charge. A current of 10 amps is flowing through the sample perpendicular to the magnetic field. This manual is intended to provide a general guidance for the lab. If an electric current flows through a conductor in a magnetic field, the magnetic field exerts a transverse force on the moving charge carriers which tends to push them to one side of the conductor. The semiconductor materials, lecture notes for mse 223 by e. Hall effect ndoped semiconductor se7260 products pasco.
So the hall voltage produced in the ntype semiconductor is negative. Students will measure hall coefficient and carrier charge concentration in a given semiconductor crystal which will help them to understand important concepts in. Hall field is defined as the field developed across the conductor and hall voltage is the corresponding potential difference. Pdf simple notes on hall effect nishad tn academia. We will study the hall effect in a parallelepipedic semiconductor sample of sizes a, b, c see figure 1. However, it was not until the twentieth century that the atomic theory of matter became firmly established as an unassailable, demonstrated fact. J x qn where j is the current density, n is the number of carriers and q is the charge defining the hall coefficient, r h 1qn, then e y v x. Hall effect in semiconductors drift velocity for an electron in the xdirection is. This is most evident in a thin flat conductor as illustrated. The hall voltage is much more measurable in semiconductor than in metal i.
Hall effect sensors are based on a thin film of semiconducting material typically indium arsenide in which a voltage perpendicular to an applied current and an applied magnetic field appears fig. The temperature range of this experiment is 77k to 400k at its most extreme. California polytechnic state university solid state physics laboratory hall effect 121 experiment 12. As a result, the potential difference is developed between the upper and bottom surface of the ntype semiconductor. The hall effect the hall effect describes the behavior of the free carriers in a semiconductor whenapplying an electric as well as a magnetic field. The hall effect 1, 2 has proved to be a convenient and useful tool for probing charge transport properties in the solid state and is routinely used as a standard materials characterization method. Pdf she hall effect in semiconductor semantic scholar. Significance of the hall effect on semiconductors gulpmatrix. The hall effect is the production of a potential difference due to the motion of a conductor through an external magnetic field. Ph 3455mse 3255 the hall effect in a metal and a ptype. When a current carrying semiconductor is placed in a magnetic field, the charge carriers experience force in the direction which is perpendicular to the flow of current and magnetic field, which results in development of voltage. Semiconductor hall effect basic concepts, numerical on. Carrier density and mobility can also be calculated. Hall effect in ptype semiconductor if the magnetic field is applied to a ptype semiconductor, the majority carriers holes and the minority carriers free electrons are pushed down towards the bottom surface of the ptype semiconductor.